Since this hasn't been answered, I'll have a go. Usually, this is something to do with the "overscan" or "scaling" setting on the display itself, not the driver/card setup. It's unique to HDMI, which is why your DVI equipped display doesn't show the "problem" (it's actually a feature, but not in this situation), and you'll need to go through your OSD menu and find the relevant bit to tweak. On mine it would be scaling, set to 1:1 to disable overscan.